1. Field of the Invention
The present invention relates to surgical instruments known as trocars which are used in endoscopic surgery to pierce or puncture an anatomical cavity to provide communication with the cavity during a surgical procedure. More particularly, the present invention relates to an improved flapper valve assembly for communication with bore of the trocar.
2. Description of the Prior Art
Endoscopic surgery is an essential method of performing surgical operations and has become the surgical procedure of choice, because of its patient care advantages over xe2x80x9copen surgery.xe2x80x9d More particularly, a form of endoscopic surgery is laparoscopic surgery. A significant advantage of laparoscopic surgery over open surgery is the decreased post-operative recovery time. In most instances, a patient is able to leave the hospital within hours after laparoscopic surgery has been performed, whereas with open surgery, a patient requires several days of hospital care to recover. Additionally, laparoscopic surgery achieves descreased incidents of post-operative abdominal adhesions, decreased post-operative pain, and enhanced cosmetic results.
Conventionally, a laparoscopic surgical procedure begins with the insulation of the abdominal cavity with carbon dioxide. The introduction of this gas into the abdominal cavity lifts the abdominal wall away from the internal viscera. The abdominal wall is then penetrated with a device known as a trocar, which includes a housing assembly, a cannula assembly attached to the housing assembly to form a bore through the trocar, and a piercing element called an obturator. The obturator slides through an access port formed on the upper end of the housing assembly and through the bore of the trocar. After insertion of the trocar through the abdominal wall of the patient, the obturator is removed by the surgeon while leaving the cannula or tube protruding through the body wall. Laparoscopic instruments can then be inserted through the cannula to view internal organs and to perform surgical procedures.
However, once the obturator is removed from the bore of the housing, it is necessary to obstruct the access port so that the carbon dioxide gas introduced into the abdominal cavity of the patient is contained. Traditionally, a flapper valve having a removable non-metallic seal is used to regulate communication via the access port. For example, the trocar disclosed in U.S. Pat. No. 6,238,407 uses a flapper valve with a removable rubber or silicon seal to insure the access port is tightly secured once the obturator is removed.
While the removable rubber or silicon seal provides an excellent means to secure the access port during laparoscopic surgery, the use of such non-metallic seals have undesirable results as well. Non-metallic seals are not as resilient to mechanical, chemical, and thermal wear as the surrounding metal components of the trocar. Therefore, non-metallic seals must be disposed of and replaced after operational use and wear due to chemical and high temperature sterilization procedures. Maintenance and replacement procedures require the trocar to be disassembled and reassembled thereby expending valuable time and resources.
Accordingly, it would be desirable to have a trocar with a flapper valve and sealing means being fabricated entirely of durable metal and providing a metal-to-metal seal for the access port without the use of non-metallic sealing agents. This novel and useful result has been achieved by the present invention.
In accordance with the present invention, a trocar is provided which comprises a metal housing assembly having an upper and lower ends. An access port is formed in the upper end of the housing assembly. A sealing, metal protrusion is shaped to fit the access port of the housing and meshes with its mating seal component. Communication via the access port is regulated by a flapper valve sub-assembly. The flapper valve comprises a metal flapper door having a protrusion formed thereon and a recessed ring formed around the protrusion. The flapper door has a xe2x80x9cclosedxe2x80x9d position where the access port is obstructed and a range of xe2x80x9copenxe2x80x9d positions where communication via the access port is unobstructed. In the xe2x80x9cclosedxe2x80x9d position, the configuration of the flapper door contacts and seals against the access port""s mating metal seal configuration in the trocar housing. This results in a consistent, normal wear resistant, metal to metal seal across the mating surfaces of the access port and flapper valve mechanism. Furthermore, the flapper valve incorporates a device for biasing the flapper door in the xe2x80x9cclosed and sealedxe2x80x9d position and provides required force to achieve desired pressure seal.
A trocar in accordance with the present invention further comprises a cannula assembly attached to the lower end of the housing assembly to define a bore therethrough. The cannula assembly is axially aligned with the access port of the housing assembly.
A trocar in accordance with the present invention also comprises an obturator assembly for sliding engagement in the bore. The obturator has a piercing end which slides into the access port of the housing assembly and rotates the flapper valve to the open position. With communication established through the access port, the obturator may slide through the bore of the trocar defined by the cannula assembly and penetrate the abdominal wall of the patient. Once the obturator is removed from the trocar, the flapper valve resets to the closed position to obstruct communication through the bore of the trocar.